Antarctica
Antarctica Niche
Description of Niche
Sea Ice Slush Ross Dependency (Ross ice shelf and Ross Sea) Freshwater Lake Vostok – Lake Vostok lies beneath the Russian Research Station Vostok for which it is named. This subglacial lake has been studied since the late 1960’s yet no one has actually sampled the water within it directly. It is the Largest of the approximately 150+ subglacial lakes (Inman) comparable in size to Lake Ontario with approximately 5000 km3 of water (Studinger; Célin, et al.). It is thought that Lake Vostok has been continuously isolated from the earth’s atmosphere for the past 15-30 million years, also rendering it cut off from new carbon sources as well as light (Célin, et al) making it a very unique environment. The ice sheath moves across the lake at a speed of ~3m per year in an easterly direction.(Studinger)
Where located?
Sea Ice Slush Sea slush is located on the southernmost continent on the globe, Antarctica, which covers the South Pole and in the surrounding hydro-areas like the Ross Sea. Each type of ice reflects the age and different forms as well as thickness of ice at different stages of development. Sea slush refers to recently formed ice and characterized by snow, which is saturated and mixed with water on land or ice surfaces that grow to no more than 10cm thick. (1)
Ross Dependency (Ross ice shelf and Ross Sea) Freshwater Lake Vostok – Lake Vostok is located in East Antarctica under approximately 4km of ice. The ice sheath varies in thickness from the northern to the southern region. (Studinger)
===Physical Conditions?===What are the conditions in your niche? Temperature, pressure, pH, moisture, etc. Sea Ice Slush Ross Dependency (Ross ice shelf and Ross Sea) Freshwater Lake Vostok k – Lake Vostok, like many other subglacial lakes holds many extreme physical conditions, ranging from high pressure ~350 atm, low temperatures (between -3 and 8°), and permanent darkness. (Steigert) The high pressure exuded from the ice above Lake Vostok keeps it liquid, since water freezes at a lower temperature when under high pressure.(Karl, et al. 1999) ===Influence by Adjacent Communities (if any)=== Is your niche close to another niche or influenced by another community of organisms? Sea Ice Slush Ross Dependency (Ross ice shelf and Ross Sea) Freshwater Lake Vostok – Lake Vostok was thought to have been not only isolated from the 20th century atmosphere but also from any other surrounding environments. This thinking has now changed as recent imaging studies have shown that these subglacial lakes are potentially connected through a network of rivers. This makes sterile drilling all the more important since if one lake gets contaminated the chances of other subglacial lakes becoming contaminated increases, especially those downstream from the test site. (Studinger) Also, the actual lake itself is in constant balance with the accretion ice above it. The ice melts in the northern part of Lake Vostok possibly delivering nutrients and other microorganisms into the lake. (Studinger) As the ice in the northern region of Lake Vostok melts it sinks to the lake floor, where it is warmed via geothermal activity and/or pressure. As the waters temperature increases it also becomes less dense causing it to rise to the surface in the south. Once the water has resurfaced in the south it freezes and becomes part of the accreted ice. This water movement is important in considering the ice core samples. As the water rises to the surface it can bring some of the sediment and the organisms which reside on the lake floor or event throughout the varying depths with it causing it to become trapped in the ice. The coring at Lake Vostok has penetrated into the accretion zone in the southern portion of the lake. (The accretion zone is the lowest 210m, and the core sample was taken from 150m above the lake)(Steigert) As the ice moves across the sediment a small amount of the sediment becomes entrapped. According to Christner et al., this provides a mechanism by which organism can get transferred into Lake Vostok.
===Conditions under which the environment changes=== Do any of the physical conditions change? Are there chemicals, other organisms, nutrients, etc. that might change the community of your niche. Sea Ice Slush Ross Dependency (Ross ice shelf and Ross Sea) Freshwater Lake Vostok – Dependent on the depth of the water the physical conditions of Lake Vostok can differ. Lake Vostok has been previously thought to be an area without any seismic activity – this has now changed. A low amount of seismic activity has been noted and this leads to the potential of thermal energy as well as a possible nutrient supply. Furthermore, microseismic activity has been recorded nearby which might drive convection in the Lake. (Studinger)
Who lives there?
Sea Ice Slush Ross Dependency (Ross ice shelf and Ross Sea) Freshwater Lake Vostok – Currently there is no definite knowledge on the type of organisms which reside in Lake Vostok. There are many stipulations on the type of organisms, if any, that might be found within. They are most likely extremophiles, tolerant of extremely low temperatures (<0°C). Furthermore they would probably have an adaptation to high pressure. In recent years continued coring has indeed brought evidence of such microbes. According to Karl, et al. the organisms found within one of the core samples were found to be oligotrophic. Oligotrophic organisms live with minimal nutrients, low biomass, and also a low energy flux.(Karl) In one experiment core ice from section 3593 was melted and samples of the melt ice were spread on agar plates, enriched with various nutrients and incubated at 25°C. Four colonies were grew and 16s rDNA comparison was performed. This analysis showed that the microbes, which were produced, have similar 16s sequences. Their nearest phylogenetic neighbors are Brachybacterium conglomeratum (found in cheese), Sphingomonas sp. (found in Guliya ice core), Paenibacillus amylolyticus (found in soil), Methylobacterium sp. (found as biofilm on cooling fan), and on unidentified organism.(Christner)
Another study found fourteen different isolates which had been grown on agar. Cruptococcus sp. And Rhodoturula sp.(both in the yeast family) and the remaining twelve bacteria included Subtercola sp., sphingomaonas sp. leaving nine remaining to be identified.(Raymond)
===Which microbes are present?===You may refer to organisms by genus or by genus and species, depending upon how detailed the your information might be. If there is already a microbewiki page describing that organism, make a link to it. Sea Ice Slush Ross Dependency (Ross ice shelf and Ross Sea) Freshwater Lake Vostok Lake Vostok* Evidence suggests the presence of thermophilic chemoautotrophic microorganisms in Lake Vostok. (Célin, et al.) Hydrogenophilus thermoluteolus (Célin, et al.)
- All organisms mentioned for Lake Vostok are ones found in the accretion ice above Lake Vostok.
===Are there any other non-microbes present?=== Plants? Animals? Fungi? etc.
===Do the microbes that are present interact with each other?=== Describe any negative (competition) or positive (symbiosis) behavior
===Do the microbes change their environment?=== Do they alter pH, attach to surfaces, secrete anything, etc. etc. Sea Ice Slush Ross Dependency (Ross ice shelf and Ross Sea) Freshwater Lake Vostok It has been thought that some of the organisms which reside in such extreme cold have an ability which allows them to change the physical structure of the ice around them. Also, these conditions warrant a slow metabolism as well as an alternate energy source. Ice binding proteins, which inhibit ice-recrystalization have been isolated out of core samples at Lake Vostok(Raymond, et al.) ===Do the microbes carry out any metabolism that affects their environment?=== Do they ferment sugars to produce acid, break down large molecules, fix nitrogen, etc. etc. Sea Ice Slush Ross Dependency (Ross ice shelf and Ross Sea) Freshwater Lake Vostok
==Current Research== Enter summaries of the most recent research. You may find it more appropriate to include this as a subsection under several of your other sections rather than separately here at the end. You should include at least FOUR topics of research and summarize each in terms of the question being asked, the results so far, and the topics for future study. (more will be expected from larger groups than from smaller groups)
Célin, et al – genetic comparisons of 16_ RNA of bacterial DNA extracted from Lake Vostok ice cores. Samples were compared from two different depths in two separate laboratories to minimize contamination. This research is being carried out in part to answer the question of potential life on other planets where there are no carbon sources available or other extreme environments. … Buford Price, et al. – Raymond, et al. –
Antarctica in current Popular science
Here are some links to Articles about Antarctica which have been published in popular science magazines. http://news.nationalgeographic.com/news/2007/12/071227-antarctica-wetland.html - “Antarctica may contain “Oasis of Life”” http://news.nationalgeographic.com/news/2007/05/070516-deep-sea.html - “Bizarre New Deep-Sea Creatures Found Off Antarctica”
http://www.caml.aq/microbes/index.html - This is a Census of Marine Aquatic life.
References
Edited by [Sabrina Koperski], students of Rachel Larsen
